The new Web browser that Google Inc. released Tuesday is designed to expand its huge lead in the Internet search market and reduce Microsoft Corp.'s imprint on personal computers.

The free browser, called "Chrome," is being promoted as a sleeker, faster, safer and reliable alternative to Microsoft's Internet Explorer, which has been the leading vehicle for surfing the Web for the past decade. Despite recent inroads by Mozilla Foundation's Firefox, Internet Explorer is still used by roughly three-fourths of the world's Web surfers.

"What we want is a diverse and vibrant ecosystem," Google co-founder Sergey Brin told reporters Tuesday during Chrome's unveiling. "We want several browsers that are viable and substantial choices."

Among other features, Chrome's navigation bar - the space where you type an Internet address - will serve a dual purpose. Users can either enter an address into the space or a search request that will be processed through their search engine of choice.

Naturally, Google bets it will be the default search engine for the majority of Chrome users, helping to build upon its nearly 64 percent share of the worldwide search market.

"You only have 24 hours a day and we would like you to do more searches," Google's other co-founder, Larry Page, said at the unveiling. "If the browser runs well, then you will do more searches."

And more queries generate more revenue for Google, whose search engine is the hub of the Internet's largest advertising network.

Google also is counting on Chrome to become the linchpin in its effort to distribute widely used computer programs like word processing, spreadsheets and calendars through the Web browser instead of as applications installed on individual machines. If the crusade is successful, it might undercut Microsoft's profits by diminishing sales of its Office software package.

"Chrome will strengthen the Web as the biggest application platform in the world," predicted Jon von Tetzchner, chief executive of the company that makes the Opera browser, which ranks a distant fourth in the market.

Microsoft, which crushed Netscape Communications to win the last major browser war in the 1990s, played down the threat from Chrome. The Redmond, Wash.-based software maker predicted that most people will embrace its latest version, Internet Explorer 8, which it released in test status last week.

"IE8 is designed to put users in control of how and where they navigate, improve their day-to-day browsing, keep people safe from real threats ... and respect people's privacy online," Dean Hachamovitch, Internet Explorer's general manager, said in a statement Tuesday.

But Benchmark Co. analyst Brent Williams thinks Microsoft has cause for concern. In a Tuesday research note, Williams described Chrome as a "a new, potentially significant, challenge to Microsoft's Web strategy and to (Microsoft's) core product suite, and indeed to (Microsoft's) business model."

Chrome may lure even more users from Firefox, which has grabbed more than 10 percent of the browser market with the help of an advertising and search alliance with Google. The ad partnership was recently extended through 2011.

Because Chrome and Google both are built on similar "open-source" models that share computer coding with outside developers to foster innovation, the products are likely to appeal to similar subsets of Web surfers looking for alternatives to Internet Explorer.

"If there is a casualty in the browser wars, it's likely to be Mozilla's Firefox," the Info-Tech Research Group predicted Tuesday.

Google executives emphasized that they wouldn't have been able to build Chrome during the past two years without the inroads already made by Firefox, and expressed hope that the two browsers will blend the best features from both products.

"I hope big chunks of Chrome make it into the next generation of Firefox," Brin said.

In a blog posting, Mozilla CEO John Lilly said he had been expecting Google to enter the browser market for some time and predicted that Firefox would continue to hold its own.

"It should come as no real surprise that Google has done something here - their business is the Web, and they've got clear opinions on how things should be, and smart people thinking about how to make things better," Lilly wrote.

Chrome hopes to set new standards for browsers by enabling Web pages and applications to run on separate tabs that won't crash if there is a problem on another tab. The tabs also can be moved around on a page or even placed on a computer desktop.

The browser also will remember a user's favorite destinations and automatically display the nine most visited Web sites in a tab. For users who don't want someone else with access to the same computer to know where they have been, Chrome includes an "incognito" tab that conceals the Web surfing activity.

Internet Explorer has a built-in advantage over Chrome and other competing Web browsers because it's pre-installed on the hard drives of most computers running on Microsoft Windows.

Although Chrome currently must be downloaded over an Internet connection, Google plans to explore deals with PC makers to put Chrome on new computers, too. Those arrangements could drive up Google's expenses, but Brin thinks it will be worth the investment if Chrome encourages people to spend more of their lives online.

"Our business does well if there is healthy Internet usage," Brin said.